In this work, a novel visible light–driven heterostructure Ag₃PO₄/MIL-100(Fe) composite photocatalyst was successfully synthesized via facile chemical deposition method at room temperature. Especially when the mass ratio of Ag₃PO₄ was 20% of MIL-100(Fe) (APM-2), it displayed the best photocatalytic performance, for which the degradation rate of tetracycline (TC) in conventional environment was 6.8 times higher than that of bare MIL-100(Fe). In addition, the effects of the initial concentration and pH of the solution on the degradation of tetracycline were also studied, and the results showed that the degradation of tetracycline was more favorable in a weakly alkaline environment. The excellent performance of Ag₃PO₄/MIL-100(Fe) composites was attributed to the fact that on the basis of having adequate photocatalytic active sites, modifying MIL-100(Fe) with an appropriate amount of Ag₃PO₄ particles can more effectively separate photogenerated electron–hole pairs. Five cycles of experiments showed that APM-2 has good photostability. Lastly, it was proved through quenching experiments that •O₂⁻, h⁺, and •OH all played corresponding roles in the degradation process, and a possible Z-scheme heterostructure photocatalytic degradation mechanism was proposed.

The Sustainable Development Goal 6 (SDG #6) of the United Nations (UN) is hinged on the provision, availability, and sustainability of water for the global populace by 2030. In a bid to achieve this goal, the quest to seek for ubiquitous and low-cost adsorbents to treat effluents laden with industrial dyes, such as methylene blue (MB), is on the increase in recent years. Acute exposure of humans to (MB) dye causes cyanosis, necrosis, and jaundice and even leads to death. In this research, zinc-modified hybrid clay composite adsorbent (materials from kaolinite and biomass (crushed Carica papaya seeds and/or plantain peel)) was developed via microwave route. This adsorbent was characterized using field emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FTIR) spectroscopy, energy-dispersive X-ray (EDX), and high-resolution transmission electron microscopy (HR-TEM). These characterization techniques confirmed the success achieved in doping hybrid clay with Zn. These adsorbents were used to sequester cationic dye (MB) from aqueous solutions and textile effluent under various experimental conditions. The adsorption and desorption data obtained were analyzed using various kinetic models, which are two-step kinetics, pseudo-first order, pseudo-second order, fractal kinetics, first-order desorption, second-order desorption, and modified statistical rate theory (MSRT) desorption models. Results showed that the adsorption of the dye occurred via several chemical interactions, while the latter models (for desorption) indicated that desorption occurred in two different desorption sites on the adsorbent surfaces, which showed that the adsorption of MB dye onto the adsorbents was stable without the emergence of any secondary pollution. Adsorption of MB was achieved within 15 min for aqueous solutions and 900 min for textile effluent, which is an improvement on previous results from other studies. The three adsorption-desorption cycles for MB uptake by the adsorbents showed that it is pragmatically applicable to treat textile effluents. Hence, low-cost composite adsorbents have a potential for the effective remediation of MB dye from textile effluents as this study confirmed.

With the acceleration of China’s urbanization process, construction activities have led to a substantial increase in construction waste. However, as China’s construction waste recycling rate is low, it is difficult to convert construction waste into valuable products for the sustainable development of waste resources. The biggest reason for this is the construction waste industrial chain, which is imperfect and has many problems. In this study, a simulation model is established using system dynamics software Vensim PLE. The analogue simulation shows that (1) China generates a large amount of construction waste every year. If construction waste source reduction measures are implemented, it will inhibit 50% of the waste generated. Upstream enterprises in the industry chain should actively develop waste reduction technology and improve waste reduction management; (2) marginal effect exists in the single waste reduction measure, but the government should implement more portfolio reduction measures to enhance the reduction effect, which is often three times that of the single policy; (3) the middle stream recycling enterprises in the industry chain cannot solely rely on government subsidies to reduce the cost of waste recycling. It is necessary to create synergistic linkages with more responsible entities upstream and downstream of the industry chain, thus creating a new model in construction waste management. (4) Government policies tend to drive the purchasing power of building material market. The government should actively exert its subjective initiative, supervise and provide policies to help the downstream enterprises that supply recycled building materials in the industry chain, and change the rigid understanding of contractors and owners about recycled building materials. The research conclusions can provide theoretical guidance for industry chain-related enterprises and government management departments in policy formulation, so that construction waste is sustainably developed.

Feeding 9 billion by 2050 is one of major challenges for researchers. Use of diversified crops, nonconventional water resources and rehabilitation of marginal lands are alternate options to produce more food to face climate change projections. Adaptation to climate change through climate smart agriculture practices, agroecology activities, and crop-based management packages can help transform the marginal lands from environmental burdens into productive and economic blocks. This review discusses the recent advancements on specialty group of alternate crops (oil seeds, legumes, cereals, medicinal, lignocellulose, and fruit crops) which can adapt in the marginal environments. Availability of alternate water resources (saline water, treated wastewater) for irrigation cannot be omitted. Crop diversification systems involving drought and salt-tolerant crops are likely to be the key to future agricultural and economic growth in the regions where salt-affected soils exist and/or saline aquifers are pumped for irrigation. These systems may tackle three main tasks: sustainable management of land resources and enhancement of per unit productivity; intensification of agroecological practices to increase soil fertility; and improving productivity of marginal lands for diversified climate smart crops. This review explores various aspects of marginal lands and selection of tolerant crop genotypes, crop diversification, and agroecological practices to maximize benefits.

Azospirillum brasilense Cd is a bacterial strain widely used as an inoculant of several crops due to its plant growth promoting properties. However, its beneficial effects depend on its viability and functionality under adverse environmental conditions, including the presence of arsenic (As) in agricultural soils. Therefore, the aim of this work was to evaluate the response of A. brasilense Cd to arsenate (AsV) and arsenite (AsIII). This bacterium was tolerant to As concentrations frequently found in soils. Moreover, properties related to roots colonization (motility, biofilm, and exopolymers) and plant growth promotion (auxin, siderophore production, and N₂ fixation) were not significantly affected by the metalloid. In order to deepen the understanding on As responses of A. brasilense Cd, As resistance genes were sequenced and characterized for the first time in this work. These genes could mediate the redox As transformation and its extrusion outside the cell, so they could have direct association with the As tolerance observed. In addition, its As oxidation/reduction capacity could contribute to change the AsV/AsIII ratio in the environment. In conclusion, the results allowed to elucidate the As response of A. brasilense Cd and generate interest for its potential use in polluted environments.

Ammonia (NH₃) volatilization from paddy soils is a main source of atmospheric NH₃ and the magnitude is affected by many factors. Because of the complex field condition, it is difficult to identify the relative importance of individual factor on NH₃ volatilization process in different locations and at different times. In this study, the grey relational entropy method was used to evaluate the relative impact of four main factors (i.e., nitrogen fertilizer application rate, NH₄-N concentration, pH, and temperature of the floodwater) on NH₃ volatilization loss from three different field experiments. The results demonstrated that floodwater NH₄-N concentration was the most important factor governing NH₃ volatilization process. Floodwater pH was the second most important factor, followed by temperature of the floodwater and nitrogen fertilizer application rate. We further validated the grey relational entropy method with NH₃ volatilization loss data from other published study and confirmed the order of importance for the four factors. We hope the findings of this study will be helpful for guiding design to reduce paddy soil NH₃ emission.

Knowledge on the variability in quantity and compositions of various size groups of aerosols is important to understand their sources and their role in biogeochemical and climate processes. Here, we studied total suspended particles (TSP), PM₁₀ and PM₂.₅ for their quantitative and water soluble compositional (F⁻, Cl⁻, SO₄²⁻, NO₃⁻, NH₄⁺, Na⁺, K⁺, Ca²⁺, and Mg²⁺) distributions, and to understand their nature and potential sources at Goa and Visakhapatnam on the west and east coasts, respectively, of India. While the mean concentrations of TSP were found to be 117 ± 44 and 85 ± 51 μg/m³ its maximal levels occurred in spring intermonsoon (SIM; 141 ± 52) and winter monsoon (WM; 155 ± 145 μg/m³) seasons at Goa and Visakhapatnam, respectively. PM₁₀ and PM₂.₅ exhibited higher ranges at Visakhapatnam than Goa. The increase in PM₂.₅ abundance from WM to SIM at Visakhapatnam seems to occur in coincidence with decrease in TSP favored by topography and ambient meteorological conditions. Locally released and seasonally transported (from land and sea) constituents contributed to the observed variability in aerosol compositions. Sulphate dominated the aerosol composition at both Goa (57–64%) and Visakhapatnam (43–55%) followed by NO₃⁻ (5–16% and 6–18%, respectively) where the former component was higher in PM₁₀ and PM₂.₅. The NO₃⁻ was more in TSP. Relations between SO₄²⁻ and NH₄⁺ suggested possible presence of NH₄HSO₄. Examination of ionic ratios and balance suggested near neutrality in PM₁₀ and PM₂.₅ while TSP was acidic at the both locations. Notable relations between Ca²⁺ and NO₃⁻, particularly in PM₁₀ at Goa, indicated their release from mining related activities.

An evaluation of the history of anthropogenic mercury (Hg) emissions is needed to quantify total atmospheric Hg emissions since the Industrial Revolution. Thus more long-term records of Hg accumulation rate from natural archives are needed. In the present study, a sediment core from Tianchi Lake, a crater lake in northeastern China, was used to reconstruct atmospheric Hg accumulation rates during the past 800 years. The results show that both Hg concentration and Hg accumulation rate began to increase from 29.5 to 40.2 ng g⁻¹ and from 1.44 to 2.26 μg m⁻² yr⁻¹, respectively, at ~ 1750 AD, synchronous with the initiation of the Industrial Revolution. The Hg accumulation rate and Hg concentration increased significantly at ~ 1850 AD, and subsequently, there were two prominent peaks, at ~ 1940 AD and ~ 1980 AD, which are temporally consistent with the Second World War and the peak in commercial usage of Hg, respectively. The Hg accumulation rate and Hg concentration decreased after ~ 1980 AD, possibly because of the decrease in the global Hg background at that time. Differences in regional Hg emissions and atmospheric circulation may be responsible for the different trends in Hg accumulation rate after ~ 1980 AD in the Tibetan Plateau and northeastern China. Our results provide new data for evaluating natural and anthropogenic Hg emissions to the atmosphere in China.

There are a lack of systematic studies comparing the effects of foliar-applied selenium (Se) with different Se sources at different growth stages in wheat. Herein, we biofortified wheat via the foliar application of selenite and selenate at different rates and different stages under field conditions. Results showed that foliar-applied selenate and selenite had no significant effect either on wheat biomass or grain yield (p < 0.05). Selenium distribution in different parts of wheat plant ranked decrease as leaf > root > grain > glume > stem with selenite treatment, and it appeared in the decline order as leaf > grain > glume > stem > root with selenate treatment. These results suggested that biofortification with selenate caused, relatively to selenite, a higher accumulation of Se in grains. Foliar application of Se of either selenate or selenite at pre-filling stage was superior in improving the Se concentration of wheat grains than application at pre-flowering stage. Meanwhile, organic Se comprised about 72–93% of total Se in wheat grains, which was reduced by 5.8% at high Se rate (100 g ha⁻¹), irrespective of the forms of Se or stages applied. The organic Se proportion in wheat grains was 9% higher with the selenate treatment than with the selenite treatment. Selenomethionine (SeMet) was the main organic species (67–86%) in wheat grains, followed by selenocysteine (SeCys₂). In summary, our results indicate that Se biofortification of wheat is most effective with 20 g ha⁻¹ selenate foliar-applied at pre-filling stage.

In this study, corn stalk was modified by manganese (Mn) before (MBC₁) and after (MBC₂) pyrolysis at different temperatures (400~600 °C) under anaerobic conditions for Cd sorption in both water and soil. Batch experiments in aqueous solution were conducted to evaluate the optimum sorption capability by biochar with and without manganese-modified. Both types of manganese modification can improve the sorption capacity of Cd(II) on biochar, which is superior to the corresponding pristine biochar without modification, especially, pyrolyzed at 500 °C with 5:1 modification ratio. Under the optimal preparation conditions, the sorption percentage on MBC₂ was 11.01% higher than that of MBC₁. The maximum sorption capacity of MBC₂ was 191.94 mg g⁻¹ calculated by isotherm model. The performance of MBC₂ was also verified in soil stabilization experiments in Cd-contaminated soil. We can conclude from the results of BCR extraction that all the application rates of MBC₂ (1%, 2%, and 3%) can reduce the mild acid-soluble fraction Cd. The reducible, oxidizable, and residual fraction Cd showed an upward trend, thus controlling the migration, transformation, and enrichment of Cd in soil. The characteristic analysis showed biochar has more irregular fold and more particle-aggregated surface after modification. The main components of these aggregated particles are manganese oxides (MnOₓ) with high sorption capacity, such as the MnOₓ crystal structure loaded on MBC₂ is a mixed structure of δ-MnO₂ and MnO. However, these particles may block the biochar pores, or some of the pores may collapse at high temperatures during the modification process. The specific surface area was reduced, even if the sorption effect of MBC was strongly enhanced. Meanwhile, under the action of the secondary pyrolysis of MBC₂ modification process, the MBC₂ has a higher degree of aromatization with more potential active sorption sites for Cd. The study concluded that the MBC₂ could be a promising amendment for Cd in both water and soil real field applications.